Peak Design Travel Backpack 45L.

I've cycled through four travel backpacks in five years of writing about gear, and this is the first one I haven't already started shopping to replace. The expansion zip is the whole pitch — 35 liters collapsed for city weekends, 45 unzipped for the six-week version of a trip — and it actually delivers, without the bag looking like a different, worse-packed object at either size.

The clamshell opening is what sold me in daily use. No more digging through a top-loader at 6am for a charging cable buried under three days of laundry; the whole bag opens flat like a suitcase, and everything inside stays visible and strapped down. It handled a genuinely bad rainstorm outside Chiang Mai's night bazaar without a drop reaching the laptop sleeve, and eighteen months of overhead-bin abuse hasn't cracked a single zipper pull.

The complaints are minor and mostly about tradeoffs, not defects: it's not light, the side-access pocket gets fiddly once the main compartment is expanded, and the price will make anyone used to a $60 backpack wince. None of that has moved me to unpack it for good.